With increasing miniaturization, integration, and reduced weight of electrical/electronic appliances, it is becoming increasingly necessary to make a module of inner parts. For example, both electric conductivity and mechanical strength are required for an inner frame requiring EMI/RFI shielding, and both EMI/RFI shielding and excellent appearance are required for exterior materials requiring EMI/RFI shielding. Conventionally, a combination of materials, each with a different function, have been used to provide the required different functions of the end material, but there is an increasing desire to use materials with multiple functions. Further, high productivity of materials is necessary to meet demands for mass production.
Improved electromagnetic shielding efficiency is increasingly required in the modern world because of increased exposure to electromagnetic waves emitted by highly integrated, highly efficient, and high power consumption electrical/electronic appliances, which can cause system malfunctions or damage to humans.
A traditional method of shielding electromagnetic waves uses metal material coating or plating. The electromagnetic wave shielding efficiency is high through surface reflection, because the metal material has high electric conductivity. So, even a thin layer of metal can efficiently shield electromagnetic waves.
However, metal coating and plating processes can be expensive, can have limited, productivity and can raise environmental concerns. For example, metal plating processes can include complicated steps such as degreasing, etching, neutralization, activating, promotion, metallizing, first plating, second plating and third plating.